Glad you asked...
Take a board and color a circle with different colored wedges related to your subject. Buy a spinner set at your local craft store, and click int onto the center of the board.
Then again, this answer might help you...
It is pretty easy to make a game spinner for your game at home. It requires very little in the way of materials and is fairly easy to put together as well. For more information look here: http://literacy.kent.edu/Oasis/PACT/spin...;

